What is the middle lamella in a plant cell composed of?

$A$ mature plant cell has . . . . . . .

The cytoplasm of one cell is connected to another through:

$RBC$ and a plant cell (with thick cell wall) are placed in distilled water. The solute concentration is the same in both the cells. What changes would be observed in them?

The middle lamella is primarily composed of:

Polygalacturonoids (pectins) are the major constituents of: